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Klasyfikacja obrazów w tomografii komputerowej z wykorzystaniem głębokich sieci neuronowych

Podolszańska Jolanta

Inżynier i Fizyk Medyczny

2020

Vol. 9, nr 4

235--237

Głębokie uczenie jest podkategorią uczenia maszynowego, które polega na tworzeniu wielowarstwowych sieci neuronowych, naśladując tym samym wykonywanie zadań przez ludzki mózg. Algorytmy głębokiego uczenia są ułożone według rosnącej złożoności, dlatego możliwe jest stworzenie systemów do analizy dużych zbiorów danych. Proces uczenia odbywa się bez nadzoru, a program buduje samodzielnie zestaw cech do rozpoznania. Artykuł przybliża na czym polega owa klasyfikacja obrazu tomograficznego.

Deep learning is a subcategory of machine learning, which involves the creation of multilayer neural networks, mimicking the performance of tasks by the human brain. Deep learning algorithms are arranged according to increasing complexity, so it is possible to create systems to analyze large data sets. The learning process takes place unsupervised, and the program builds a set of features to recognize. The article presents the classification of the tomographic image.

An Orientation-space Super Sampling Technique for Six-dimensional Diffraction Contrast Tomography

Viganò N., Batenburg K. J., Ludwig W.

Fundamenta Informaticae

2016

Vol. 146, nr 2

219--230

Diffraction contrast tomography (DCT) is an X-ray full-field imaging technique that allows for the non-destructive three-dimensional investigation of polycrystalline materials and the determination of the physical and morphological properties of their crystallographic domains, called grains. This task is considered more and more challenging with the increasing intra-granular deformation, also known as orientation-spread. The recent introduction of a sixdimensional reconstruction framework in DCT (6D-DCT) has proven to be able to address the intra-granular crystal orientation for moderately deformed materials. The approach used in 6D-DCT, which is an extended sampling of the six-dimensional combined position-orientation space, has a linear scaling between the number of sampled orientations, which determine the orientation-space resolution of the problem, and computer memory usage. As a result, the reconstruction of more deformed materials is limited by their high resource requirements from a memory and computational point of view, which can easily become too demanding for the currently available computer technologies. In this article we propose a super-sampling method for the orientation-space representation of the six-dimensional DCT framework that enables the reconstruction of more deformed cases by reducing the impact on system memory, at the expense of longer reconstruction times. The use of super-sampling can further improve the quality and accuracy of the reconstructions, especially in cases where memory restrictions force us to adapt to inadequate (undersampled) orientation-space sampling.